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211 results on '"RONCI, F."'

1. Atomic structure of the single step and dynamics of Sn adatoms on the Si(111)-\sqrt{3}\times\sqrt{3}-Sn surface

Author

Zhachuk, R. A., Rogilo, D. I., Petrov, A. S., Sheglov, D. V., Latyshev, A. V., Colonna, S., and Ronci, F.

Subjects
Condensed Matter - Materials Science
Abstract

The atomic structure of well-ordered single steps on the Si(111)-\sqrt{3}\times\sqrt{3}-Sn surface and the dynamics of Sn adatoms in the vicinity of these steps was studied. The work was performed using low-temperature scanning tunneling microscopy (STM) and ab initio calculations based on the density-functional theory. The STM tip was used to record the tunneling current versus time on top of oscillating adatoms, keeping the feedback loop turned off. The dynamics of adatoms, detected as the telegraph noise present in the tunneling current, was registered near the steps at 80 K. The atomic structure model of the single steps consisting of Sn atomic chains along the steps was developed. This structure leads to the formation of potential double wells near the steps acting as traps for Sn atoms and explains the fluctuating current recorded in these areas., Comment: 9 pages, 8 figures

Published
2021
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4. First-principles calculations and bias-dependent STM measurements at the alpha-Sn/Ge(111) surface: a clear indication for the 1U2D configuration

Author

Gori, P., Ronci, F., Colonna, S., Cricenti, A., Pulci, O., and Lay, G. Le

Subjects
Condensed Matter - Materials Science
Abstract

The nature of the alpha-Sn/Ge(111) surface is still a matter of debate. In particular, two possible configurations have been proposed for the 3x3 ground state of this surface: one with two Sn adatoms in a lower position with respect to the third one (1U2D) and the other with opposite configuration (2U1D). By means of first-principles quasiparticle calculations we could simulate STM images as a function of bias voltage and compare them with STM experimental results at 78K, obtaining an unambiguous indication that the stable configuration for the alpha-Sn/Ge(111) surface is the 1U2D. The possible inequivalence of the two down Sn adatoms is also discussed., Comment: Submitted to PRL

Published
2008

13. High graphene permeability for silicon atoms during deposition at room temperature: the role of defects

Author

Ronci, F., Colonna, S., Flammini, R., De Crescenzi, M., Scarselli, M., Salvato, M., Berbezier, I., Jardali, F., Lechner, C., Pochet, P., VACH, HOLGER, Castrucci, P., Istituto di Struttura della Materia (CNR-ISM), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Dipartimento di Fisica [Roma Tor Vergata], Università degli Studi di Roma Tor Vergata [Roma], Institut des Matériaux, de Microélectronique et des Nanosciences de Provence (IM2NP), Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes (UGA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Consiglio Nazionale delle Ricerche [Roma] (CNR), and Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)

Subjects
Condensed Matter::Materials Science, ab initio molecular dynamics, Physics::Atomic and Molecular Clusters, Silicene, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Graphene, Scanning tunneling microscopy, Graphene intercalation, 2D Si clusters
Abstract

International audience; Graphene (Gr) is known to be an excellent barrier preventing atoms and molecules to diffuse through it. This is due to the carbon atom arrangement in a two-dimensional (2D) honeycomb structure with a very small lattice parameter thus forming an electron cloud that prevents atoms and molecules crossing. Nonetheless at high temperature of annealing, intercalation of atoms through graphene occurs, opening the path for formation of vertical heterojunctions formed of two-dimensional layers. In this paper, we report on the ability of silicon atoms to penetrate the graphene network, fully epitaxially grown on a Ni(111) surface, even at room temperature. Our scanning tunneling microscopy (STM) shows that defects like vacancies and dislocations of the graphene lattice favor the Si intercalation below the Gr layer forming two-dimensional, flat and disordered islands. Ab-initio molecular dynamics calculations confirm that Gr defects are necessary for Si intercalation at room temperature and show that a hypothetical intercalated silicene layer cannot be stable for more than 8 ps and that the corresponding Si atoms completely lose their in-plane order resulting in a random planar distribution and form strong covalent bonds with Ni atoms.

Published
2020
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17. High-resolution in-situ structural measurements of the Li (sub)4/3 Ti (sub)5/3 O (sub)4 'zero-strain' insertion material

Author

Ronci, F., Reale, P., Scrosati, B., Panero, S., Albertini, V. Rossi, Perfetti, P., Michael, M. di, and Merino, J. M.

Subjects
Chemistry, Physical and theoretical -- Research, Lithium -- Physiological aspects, Titanium -- Physiological aspects, Oxygen -- Physiological aspects, Diffraction -- Physiological aspects, Cells -- Analysis, Chemicals, plastics and rubber industries
Published
2002

19. Physical and chemical properties of nanocomposite polymer electrolytes

Author

Croce, F., Curini, R., Martinelli, A., Persi, L., Ronci, F., Scrosati, B., and Caminiti, R.

Subjects
Chemistry, Physical and theoretical -- Research, Electrolytes -- Research, Lithium cells -- Research, Polyelectrolytes -- Research, Chemicals, plastics and rubber industries
Abstract

Research into the chemical and physical properties of a new class of lithium conducting polymer electrolytes formed from the dispersal of ceramic powders into a poly(ethylenoxide) (PEO)-lithium salt, LiX complexes, is reported.

Published
2000

24. Topologization of Beta-Antimonene on Bi2Se3 Via Proximity Effects

Author

Física de materiales, Materialen fisika, Holtgrewe, K., Mahatha, S. K., Sheverdyaeva, P. M., Moras, P., Flammini, R., Colonna, S., Ronci, F., Papagno, M., Barla, A., Petaccia, Luca, Aliev, Ziya S., Babanly, Mahammad B., Chulkov, Evgueni V., Sanna, S., Hogan, C., Carbone, C., Física de materiales, Materialen fisika, Holtgrewe, K., Mahatha, S. K., Sheverdyaeva, P. M., Moras, P., Flammini, R., Colonna, S., Ronci, F., Papagno, M., Barla, A., Petaccia, Luca, Aliev, Ziya S., Babanly, Mahammad B., Chulkov, Evgueni V., Sanna, S., Hogan, C., and Carbone, C.

Abstract

Topological surface states usually emerge at the boundary between a topological and a conventional insulator. Their precise physical character and spatial localization depend on the complex interplay between the chemical, structural and electronic properties of the two insulators in contact. Using a lattice-matched heterointerface of single and double bilayers of beta -antimonene and bismuth selenide, we perform a comprehensive experimental and theoretical study of the chiral surface states by means of microscopy and spectroscopic measurements complemented by first-principles calculations. We demonstrate that, although beta -antimonene is a trivial insulator in its free-standing form, it inherits the unique symmetry-protected spin texture from the substrate via a proximity effect that induces outward migration of the topological state. This "topologization" of beta -antimonene is found to be driven by the hybridization of the bands from either side of the interface.

Published
2020

31. The role of kinetics on the Mn-induced reconstructions of the GaAs(001) surface.

Author

Colonna, S., Placidi, E., Ronci, F., Cricenti, A., Arciprete, F., and Balzarotti, A.

Subjects
GALLIUM arsenide, MANGANESE compounds, ELECTRON diffraction, EVAPORATION (Chemistry), ANNEALING of crystals
Abstract

A combined scanning tunneling microscopy and low-energy electron diffraction investigation of the Mn/GaAs(001) interface formation is reported. The interface, grown on a (2 × 4) reconstructed substrate produced by molecular beam epitaxy, was studied as a function of Mn evaporation with thickness ranging from 1/8 ML to 1 ML. The interaction of Mn atoms with the semiconductor surface is strong and leads to surface reconstructions involving a rearrangement of the two outmost atomic layers of the substrate. For Mn thickness lower than 1/2 ML, the surface is characterized by a (2 × 1) periodicity. Conversely, when the Mn deposition is increased to 1/2 ML the surface reconstruction is strongly dependent on the preparation procedure. If Mn deposition is performed on the substrate at 390 °C, a fully ordered surface characterized by a clear (2 × 2) reconstruction is obtained, whereas, annealing the sample after Mn deposition, gives a disordered surface with a (2 × 1) symmetry. An intermediate phase between (2 × 1) and (2 × 2) is found for Mn depositions in between 1/4 and 1/2 ML. No further structural evolution was observed for both preparation methods above 1/2 ML coverage. [ABSTRACT FROM AUTHOR]

Published
2011
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33. Evidence ofβ-antimonene at the Sb/Bi2Se3interface

Author

Flammini, R, primary, Colonna, S, additional, Hogan, C, additional, Mahatha, S K, additional, Papagno, M, additional, Barla, A, additional, Sheverdyaeva, P M, additional, Moras, P, additional, Aliev, Z S, additional, Babanly, M B, additional, Chulkov, E V, additional, Carbone, C, additional, and Ronci, F, additional

Published
2018
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35. In situ energy dispersive X-ray diffraction study of LiNi0.8Co0.2O2 cathode material for lithium batteries

Author

Ronci, F., Scrosati, B., Albertini, Rossi V., and Perfetti, P.

Subjects
Nickel compounds -- Research, Nickel compounds -- Electric properties, Lithium compounds -- Research, Lithium compounds -- Electric properties, Chemistry, Physical and theoretical -- Research, Chemicals, plastics and rubber industries
Abstract

The structural variation of the electrode material was studied in situ as a function of x during the first 7 cycles by means of the energy dispersive X-ray diffraction. Extending the anodic voltage limit to higher values resulted in an even deeper deintercalation, which reflects a more drastic reduction of the c parameter and of the unit cell volume.

Published
2001

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